Sun compass



May 18, l948. J. M. s.- KAUr-'MAN Er AL SUN coMPAss Filed July 6, 1945 3 Sheets-Sheet l 7m MW ohm. .an i

May 18, 1948 t l J. M. s. KAUFMAN Erm. 2,441,636

SUN COMPASS Filed July 6, 1945 3 Sheets-Sheet 2 May 18, 1948. J..M. s. KAUFMAN Er AL 2,441,636

SUN coMPAss Filed July 6, 1943 3 Sheets-Sheet 3 Patented May 18,11948 SUN COMPASS Joseph M. S. Kaufman, Washington, D. C., and Shelley Krasnow, Arlington, Va.

Application July 6, 1943, Serial No. 493,674

Claims.

This-invention relates to navigational and directing instruments, for indicating a `course or path by means of a shadow cast upon an appropriate member. In the particular example shown herein, there is described a compass suitable for navigating and directing vehicles, making use of the suns shadow.

It is an object of the invention to provide an improved instrument by which, without the use of any intricate or delicate :clockwork mechanism, it is possible to navigate with a high degree of precision. 1

It is a further object of the invention to provide a navigating instrument for directing the course of a vehicle -or craft, Without having such instrument affectedvby Violent changes in motion Iof the craft or vehicle.

'It is a further object of the invention to provide an apparatus which can be used in north or south latitudes with equal facility, and which can be used with either the suns shadow, .or a star.

It is a further object of the'invention to provide a 'sun compass with a leveling means, the leveling means being particularly adapted to resist the heat of the sun, and to be readily visible. It is a further object of the invention to provide a relatively sturdy apparatus which may be -assembled and disassembled, or repaired, in the eld with facility and will be vparticularly adapted to processes of quantity manufacture. Reference is had tothe accompanying drawings, in which:

Figure 1 showsajp View of the assembled sun compass, ready for use.

Figure 2 shows a view of the underside of the completely assembled sun? compass, removed from its mounting on the craft or vehicle.

f Figure 3 shows a vertical cross-sectional view of the complete sun compass, taken across the plane 3-3 of Figure 1.

-Figure 4 shows a cross-sectional enlarged view ofrthe'nut, bolt and bolt lock assembly across the plane 4-4, in Figure 2.

Figure 5 vshows an enlargedcross-sectional view of the upper Vportion of the assembled unit shown in Figure 3. A

Figure 6 shows a cross-sectional view of the bushing shown in Figure, and indicates the detail of the key and keyway.

Figure 7 shows an enlarged view of the bolt lockl shown in Figure 4.

Figure 8 shows an enlarged cross-sectional view taken across the vertical plane, of the level vial andhousing shown inFigure 3.y g

Figure 9' shows the'three slghting'rods utilized with the apparatus, one of the rods being indicated in vertical cross section.

' Figure 10 shows the plan view of the date bar, giving the various indicia marked upon the said bar.

Figure 11 shows a detail of the underside of the solar plate, indicating the manner of guiding the same.

Figure l2 shows a cross-sectional view of the date bar and solar plate indicated in Figure 10, taken across the plane I 2,-I2.

Figure 13 shows an alternative method of fabricating the solar plate, indicating particularly the underside of the said plate.

Figure 14 shows a vertical cross-sectional view of the solar plate shown in Figure 13, taken across the plane I4-I4.

The sun compass .is carried on a square metal frame I, to which is afllxed in adjustably rotatable relation, a frame 2. Frame 2 is preferably provided with two drilled holes 3, near the center thereof, for attachment to a support by means of bolts 4, 4. Other means of attachment, such as clamping, welding, riveting, or any of the other commonly used mechanical means of-fastening may be utilized. The terminal portions of Vframe 2, are provided with drilled holes, through which are placed bolts 5, 5. The head of bolt '5, passes through a bolt lock 6, which is provided with two upturned flanges 1, to prevent the head of the bolt from rotating when adjustment is made. These locks are maintained in the frame I,Yby having the tongue 8, project through a drilled hole 9, in the frame I, after which the tongue is bent Over to secure locking thereof. The bolts are each provided with a metal washer I0, a lock washer I I, and a wing nut I2. By loosening wing nut I2, it becomes possible to adjust the frame I relative to the frame 2, so as to secure a desired change in the position of the frame I. At right angles .to the frame 2, a frameI3 is mounted in rotatable relationship,v somewhat similar to the relationship of frame 2 to frame I. Frame I3 contains two downwardly depending portions I4 and I5, the portion I4 preferably'being formed by bending, and the portion I5 by the afxing of a separate piece of metal by means of welding or otherwise. An elongated portion I6 projects from the frame I4, the purpose of which will be hereinafter fully described. A pin IBa is aixed permanently in frame I by welding, riveting, or otherwise, and is xed so las to be in freely rotatable relationship with a hole I1 in member I5. Attheterminal portion of member I4, there is a clamping arrangement similar to that deallow for compactness in storing and carrying the apparatus.

Frame I3 is provided with a threaded hole I3, into which is screwed the bushing 20, having an outer threaded portion, engaging the tl'ireaded` portion I3 above described. A key ZI, isfasltened into slot 22, made in bushing 23, by soldering or otherwise. Passing through ther center ofbushing 23 is a bolt 23, having a slot or keyvvay 24, which engages with the key 2l in bushing 23.

The lower portion of bolt 23, is provided with a threaded portion 25, which engages withy a nut 2 6., provided with laterally extending wings 21. A spring 28 is placed in a recess 29, in the nut 2B, and serves to maintain a slight tension on the bolt, even when the nut 23 has` been loosened. Thepupper portion of the bolt 23 is provided with a shouldered part 33, and with a centrally located threaded hole 3l, thepurpose of which will be hereinafter more fully described.

The frame I3 isv provided with. two threaded holes 32., into which pass screws 3 3, serving to hold a protractor plate 3,4. This plate is preferably circular in form, and preferably provided with graduations 35 in degrees near the. periph-v ery thereof. Holes 33 are provided to lighten the protractor without any substantialA sacrice of rigidity.

The protractor may be made Yof plastic, or. preferably of metal, such as brass, aluminum.,v stainless steel, or steel. The numerals graduations 35. or other indicia are preferably provided on the said protractor plate by. etching, and a reverse etch is preferably used, namely one` in which the figures and-graduations remain, and the background is etched away to a substantial depth.. A raised portion 31, near the periphery, and a centrally raised hub portion 33, are provided. f the unit is made by the etching. process described above, the. raised portions 31 andv 38 can be provided at the same time the numerals andl graduations 3 5 are etched. In other words, portions 31 and 33 would remainthesame height as .the graduations 35 on theperiphery, the portion 39, intermediate the. hub portion andthe periphery being etched away at the same time. as the background of the numerals and graduations. If the protractor 34 ismade. of a corrodable mate. rial, it is preferably provided with a corrosion resistant coating such. as nickelor chromium plating. In such event, it is preferable to use a dull plating and a black background. Immediately above the protractor plate 34, is 'a date bar 40, best shown in Figure 10, with a central hole- 4I, pivoting on bolt 23. The date bar has` an under flat surface d2, which bears upon the raised portions 31 and 33 upon the Vprotractor plate, when the date bar is rotated. I-nthe center of the date bar is a line 43 which extends longitudinally from one end to the other provided with-an. arrow 44, which is intended to read against the graduations 35 on the protractor plate. At therearmost portion of the 'date bar 40, is. alug 45, which is made double the thickness of. the. metal ofthe date har byv folding overas shown, and. is further provided .4 with a threaded hole 43, the purpose of which will be hereinafter more fully described. Upon the surface of the date bar, and extending from the center line are a number of graduations 41, perpendicular to the center line 43, the said lines 41, serving to indicate the correct position for the solar plate 48, depending upon the season of the year. The graduations 41 are preferably provided for4 every ten days off each month., ln order to facilitate the reading of the position of the solar plate 48 upon the date bar, the scales 41 are reproduced in duplicate at either end of the date bar and may thus be read against index 49, or the index 5D of the solar plate 48.

ln addition to. the graduations 41, above descri-bed,A anadditional set of short lines 5I are provided with numerals. These indicate the equation of time, indicating the corrections to be applied to, the reading of time for the dilerent months of the year. I ihe edges 52 of the date bei. are. machined parallel. tothe center line 43, thereof, and areialsofrnachined-so as tobe parallel to each other. It is tobe noted, thatl because of the shifting ofthe planeof theecliptic, the-.cale culations for the position of theelinesonjthedate bar, are made foragiven year, and arevalid-for that year only. However, thediierenceor error due to using ag date bar calculated;A for one.l year in a succeeding year will be ratherY small. Ifv precise results` areA desired;r separate datebars', mechanically interchangeable, can be provided; and can be changed with each change of ayear. Alternatively, where less precision can be tolerated., a. date bar- Can; recalculate@ so. est@ represent the average fer-a tenori often years,v and may beused for this4 periodi It will be noted that if. a setof-bars is .provided coverngyears: which have passed,,when they. are

placed. `*upon the instrument, they willy enable 'one' i9. dCieiIn-.inev what the. direction; 0f then shadow would have; been. fOr-erraten. time in the past Thus. the instrument becomes- Usern if it is desired i9. determiner-hema given shadow. had fallen, orshould `have fallenatrsuch time inthe past.VA Suehdata are oftenV of; importance in;mat. ters invoivinalesal testimony:

Similar-ly, interchangeable. solar' plates-canbe provided to interchange inechanically-V with; the Others.. but markedwih indiria .enablirgf-readi1l1g either greater or lesser, latitudes; I-t is: to.y be pointed. out, that it is preferableto. have-.'the instrument provided with a solarplate reading fior.v no latitudesV higher than; the: highest-v that will be encountered. Obviouslyyth;.more-lines that appear on, the. solar-- plate.` the more lrossibiiiiy .there is` Cantusion.;` f Thus.y thousnit is possible to provide plates. ,fforthe full-...99. degrees. these will in ,generali .have far more lines. than .are necessary, for general; use, which; :lines-will tend to confuse the user. Thuaga setj,of.inter chargeable. plaies can berrovided. soj that-only those latitudes which, are ofiinterest willabepro:

vided. Y

As an alternative, where theinst-rumennwillgbe used chiey.- in; bieb: latitudes Orff- On'iy-finr high latitudes, the central portion of the sol late may b e left blank;V theonter lines Still rem-a ine. 'Ihis Willi facilitatefthe-reading; Ofrthe vintime ment, particularly under the, stress of; 'adverse weather. conditions. Y v

Since navigation is generallycondueted.inge, given-latitude forA afcqnsislerablenlens airtime, only ,part kofthe lsolaV plat Similarly. graduation dlfierenttv semer-be placed-. 0r. Dati-,Ledas @une 501er righe..- endive will be.. aff-fietsten;

eating flugs' abiutv it 1 cn both sides, so 'that the plate'may be'reversed and one set of graduations orlthe othe'ruti'lized Vthe lugs being so located be moved transversely, relative to bolt 23.` Placed symmetrically on either side'of the axis 53, are four separated tabs, 56. If the solar plate is produced by stamping, these tabs are preferably stamped at thesame time asI the remainder of the plate. They are then folded underneath as shown in the-drawing, and the" position of the edges 51 of lugs 56 vadjusted soi'that when the solar plate is laid upon the date bar 40, the surfaces of 51 will engage with the surfaces 52, 52, ofthe date bar. If the tabs 56 areV properly located, and properly adjusted, they will allow longitudinal adjustment ofthe solar plate relative to the date bar without any rotational motion.

The solar plate 48 is provided with indicia on its .-upper surface. These consist of a series of concentric ellipses 58, representing latitude. In the `specific example shown, the plate has been provided with graduations up to degrees north and south latitude, although these graduations have not specically been designated as such on the drawing. A plate can be providedfor any desired value of latitude up to 90 degrees.. At 90 degrees, the ellipse will become a circle, and the outer contour will be a circle. In order to facilitate the reading ofthe lines constituting the solar plate,l it is desirablethat every other line be made wider than the others. To aid this process further, each fourth line can be made extra wide, so that the eye will easily locate the desired point. This is particularly necessary to avoid the confusion .to the eye .caused bythe network of intersecting ellipses and hyperbolas. Du'llg-chromiumplating has been found suitable fori/'the surface of the solar plate, `and for the complete date bar. The plate is preferably made symmetrical about the axes 53 and 54, in 'which case the portion of the line nearest the index 44, on the date bar ,40, will be for north latitudes, andthe portion lyingon the other side of the solar plate will be for south latitudes. A series of'hyperbolas .59, are provided, intersecting the ellipses as shown. These represent hours.. In

vthespecial case of 6:00 oclock, the hyperbola degenerates vinto a straight line, constituting the longer axis 54, of theellipse.` In the case of 12:00 oclock, the hyperbola also degenerates into 6 a straight line lying .along the short axis of .the ellipse. yAt the terminal portion of the 1.2;00 o-clock position of the ellipse, are two surfaces 4 9 and 50, Vn iachined so as to lie accurately .at right angles to the short Vaxis of the ellipse, and adjusted sothat the,V difference apart `between the surfaces 49 and 50-is equal to the distance of separation of the scales von the date bar. v

. Above the solarplate48 is a bushing 62 which fits on. the bolt 23,-and has-lyingA above it at spring 63. Above the flat spring is a pointer 64, .which fits underthehead 30ofbolt'23, and about aportion Yofthe bushing 62. Y The pointer is thus'swiveled so as to move around the center of thefbolt A2.3. i; A portion 66 .of-the frame I3 projects beyondfthe prbtractor .plate 34; 'and provided with a large bored hole 61'. "Anixed'to the portion66'of the frame .I3 i-s a casing 68, made with an. upper` shoulder' 69, and provided with two drilled threaded-'holes 10, 10. The exterior surfaceof the casing 68, is provided with avbrightly polished chromium plating to reflect the rays of the sun,.and prevent the transmission of undue heat tothe interior of themember. Beneath the member 68, is a heat-insulating washer 68a, preferably made of plastic. or other heat insulating material, adapted to. restrict the iiow of heat from. the frame I3 to the casing 68. The under- I side of the rim of flange 69, of the casing 68, is blackened, for a purpose hereinafter more fully described. Within the casing 68, is a preferably transparent level vial 12, containing liquid 13 and a bubble 14. The outer Wall of the level vial is preferably made of Pyrex glass, to insure strength and minimum expansion with changes in temperature. When the bubble 14 is viewed from above,'due to the provision of the blackened rim on the underside of flange 69, of casing 68, thebubble 14 will appear to have a black ring surrounding it. This is due to the walls of the bubble acting as a curved mirror and reecting an image of the black underside of the casing. The bubble will. thus become easily visible, even though a white background and colorless liquid is provided.' It is pointed out, however, that a liquid of any color may be utilized. If so, the color of the underside of the. flange should preferably be complementary to that of the color of the transparent liquid. Thus, if the liquid is red,

the underside of the flange may be made green or may be made black. The lever vial 12, is fastened by means of cement or'plaster v15 in the casing 68, and thus will constitute a separable member which may be easily replaced in the eld. It'is understood that when. the level vial 12 is placed in the casing 68, it is leveled, so that when the underside of thecasing 68 is on a level surface, the bubble 'will be in the center of the level vial. I

` A threaded hole 16 is provided in the portion 66 of frame I3, and serves to hold a rod, the purpose of which will be hereinafter described. Rods 11 and 18 are provided, one of these rods fitting into the threaded hole 3I in the center bolt 23, another in the threaded hole 46 of date bar 40. The rods are preferably made of steel, and are provided with threaded portions y80 at their terminal portion. A narrow sleeve 8|, threaded internally, is driven tightly onto each of the rods above named, and preferably aflixed with solder. This will provide convenient means for placing and removing the threaded rods from their corresponding threaded `holes; At the upper portion of each lof the rods` there is a threade'd'ferrule 8Ia which screws uponr the thread at the upper end of the rod. In thi-s is a smallglass capsule 82, containing radioactive luminous material.

The purpose of this willbe hereinafter described; It is understood that instead of providing a selfluminous r portion at the upper end of the rod, asrnall 'electric light bulb'may be provided," and the rod made hollowto allow the passage'vof small wires -down to a battery maintainedfin the iower part of the unit.

`Figure 13 shows an alternative method of making the solar plate. Here,a at piece 84, prefer-` ablyof metal, has a plane upper surface upon which the. indicialare marked or engraved. The

undersidefis provided with two*y arcuate.V shaped eter. If the dimension of the outer dial is reduced to approximately 3 or 4 inches, the entire unit can be made small enough to nt into a small protecting cloth or leather case, and carried in the pocket. Such a unit is particularly appropriate for use in life boats, since it will withstand rough mechanical handling, has no delicate moving parts, and will work even after it has been immersed in water.

t will be noted, that the pointer (ifi may be dispensed with, although the use of this pointer saves a great deal of fatigue in attempting to line up the shadow produced by the vertical rod ll, upon the appropriate intersection o-f the lines on the plate.

While the specific use of the sun and of the star Polaris have been mentioned in connection with the apparatus, it will be evident that it may be applied equally well to other celestial bodies, which are capable of casting a shadow either directly or indirectly, or of being sighted upon. The principles may also be utilized where an articial light is utilized, and it is desired to orient or to guide a member by means of the shadows thereof.

The apparatus herein described may also be utilized as a sun clock, for if set accurately to the actual azimuth at the location, and the solar plate is set upon the date bar to the appropriate season of the year, the shadow cast by the shadow rod will fall upon the intersection of the latitude of the particular locality and the time. It will be noted that to convert this time to actual standard time, it Will be necessary to reverse the procedure named above. In other words, the correction indicated graphically on the date bar will have to be applied with the opposite sign to that indicated, and four minutes subtracted for each degree of longitude east of the time meridian or added for each' degree west of the time meridian. The results of these operations will then give the local standard time.

It will be noted that the apparatus may be made self-leveling, by providing freely moving bearings at all of the joints of the gimbal frame, and having a weight at the lower portion of the nut 26. This will avoid the necessity of leveling the unit whenever a reading is taken, and will make unnecessary the level vial indicated,

We claim:

1. In an apparatus of the class described, a protractor plate, swiveling means in the said protractor plate, a rotating member adapted to lie upon th'e protractor plate and to rotate about the said swiveling means, the said rotatable member having a substantially plane lower surface bearing upon the said protractor plate, the said protractor plate being provided with reversed etched portions, whereby the indicia thereon will be raised relative to the background, a rim upon the said protractor plate and a center hub portion on the protractor plate being both of the same height as the indicia, with the material therebetween removed by etching, whereby the said rotatable member will bear at the hub portion and outer portion of the protractor plate respectively without frictional interference with the remainder of the said plate.

2. In a component for an instrument in which indicia are provided upon a surface and a movable member moves over and bears upon contiguous portions of the surface, raised portions constituting bearing surfaces for the said movable member, the material between the said bearing portions being relieved so as to prevent interference with the said movable member, indicia formed with a surface at the same height as the said bearing surfaces and demarcated by having the contours of the said indicia relieved to the same extent as the material between the bearing surfaces, whereby the simultaneous production of the bearing surfaces, relieved portions and indicia is facilitated.

3. In a component for an instrument, a member of attened form having indicia thereon and an element pivoted to move upon the said member and be guided by a surface thereof, the said member having the surfaces comprising the indicia and plural bearing portions all at the same height, the element moving over and bearing upon the plural bearing surfaces, the space between the bearing surfaces being relieved to the same extent as the background of the indicia.

4. 1n a component for an instrument, a dial member of flattened form having a central hub portion and an outer circumferential portion, an element resting upon and rotating about the central hub portion and bearing against the outer bearing portion, the central h'ub portion and the outer bearing portion being of the same height with material therebetween removed so as to provide relief for the moving surface of the element, indicia upon the outer portion of the said flattened membeu the said indicia having the characters thereof of the same height as the said bearing portion, with' the background for the said indiciarelieved to the same extent as the relieved portions between the bearing surfaces.

5. In an instrument component, a circular dial member having bearing surfaces over which a flattened member is guided and an outer dial portion having indicia thereon, the said dial member being circular in form, having a circular hub in the center thereof and a circular raised rim at the circumferential portion thereof, a riattened member resting upon and guided by the said central hub member and the outer circumferential portion, th'e outer circumferential portion having additionally indicia of the same height as the said raised portion with the background of the said indicia relieved, a relieved portion between the said outer circumferential portion and the central hub member with the space therebetween relieved to the same extent as the background of the said indicia.

JOSEPH M, S. KAUFMAN. SHELLEY KRASNOW.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Number Name Date 538,889 Arvidson May 7, 1895 626,791 Miller June 13, 1899 669,063 Arthur Mar. 5, 1901 699,450 Christensen May 6, 1902 849,841 Goode Apr. 9, 1907 961,862 Huntington June 21, 1910 978,093 Weule Dec. 6, 1910 1,640,166 White Aug. 23, 1927 1,820,791 Forrest Aug. 25, 1931 1,898,367 Heinze Feb. 21, 1933 2,206,003 Donnell June 25, 1940 FOREIGN PATENTS Number Country Date 537,924 Great Britain 1941 

